Hi. I have a 20 gal tank not sure if it's long or tall (it is 24" long x 16" tall X 12" deep with bogwood and a large stone, so space is an issue). It has a bigger footprint than a 10 so I don't think its tall. Anyway, when you guys put your plants in, how much space do you give between your specimens? Can you clump them together fairly closely? I have 2 Rotala Indicas and about 6 Aponogeton.